The revised aims of this project are (1) To investigate the early course of development in children with autism, examining the influence of specific child, family, and intervention factors on stability and change in the core symptoms of autism (i.e., social impairment, communication, and repetitive behaviors/interests); and (2) To investigate the psychological well-being of mothers and fathers of children with autism during early childhood, examining relations between child, family, and intervention factors on stability and change in both positive and negative well-being. This work is based in a developmental contextual framework, in which child level processes are best understood within a complex context that includes parent and family processes and the interventions available to the child and family. We hypothesize that (1) The severity of core symptoms of autism are influenced directly by the presence of co-occurring problem behaviors, competencies and the intensity of intervention services, and indirectly by the child's predisposing temperament and parental well being. (2) Parental well-being is influenced directly by parental resources, family climate, severity of the broader autism phenotype, and the child's symptoms and problem behaviors. These variables also mediate the effects of other child factors and the parents' satisfaction with the intervention services received by their child. To test these hypotheses, we plan to recruit through early intervention specialty service programs 300 18-33 month-old children diagnosed with autism and to conduct a five-year, accelerated cross-sequential longitudinal study of their development and the changes that take place in the family and in the parents' well-being. We believe that the knowledge gained will inform developmental theory and will lead to the development of more effective and responsive child and parent support interventions.